Characterization of extracellular vesicles derived from endothelial cells after co-incubation with Plasmodium falciparum-infected erythrocytes

Abstract text

Cerebral malaria (CM) affects 1% of malaria patients and is considered the most severe form of malaria. It primarily affects children under 5 years of age, is nearly 100% fatal without treatment, and often leaves survivors with severe cognitive deficits. CM pathology is characterized by a disruption of normal vascular function of the blood-brain barrier (BBB) upon adherence of Plasmodium falciparum-infected erythrocytes (IEs). To date, cytoadhesion of IEs was thought to be the main cause of BBB dysfunction. However, recent research suggests that also the activation of endothelial cells (ECs) is responsible for this severe form of pathology. The dynamics between the host immune system and malaria parasites is complex, and little is known about the immune evasion mechanisms of P. falciparum. Extracellular vesicles (EVs) may play a crucial function in disease progression, as they are essential for cell-cell communication and carry important genetic information such as microRNAs from the progenitor cell to the receiving cell. During malaria infection, the amount of EVs secreted by ECs increases significantly, which coincides with the case severity, indicating a key role for EVs during malaria pathogenesis. The purpose of this study is to investigate how infection with P. falciparum influences EVs production from human brain ECs and how they help malaria parasites to evade the immune system.In a first step EVs should be isolated by differential centrifugation and characterized using electron microscopy, nanoparticle tracking analysis, flow cytometry and miRNA sequencing. Using differential centrifugation, we were able to isolate EVs from brain ECs. Here, exosomes (100,000 x g, size 30-100 nm ) and microvesicles (18,000 x g; size 50-200 nm) could be isolated separately from each other. Furthermore, stimulation of ECs by TNF? significantly increased the secretion of EVs.In addition, there is evidence that when stimulated with IFNɣ, an important cytokine during malaria infection, no significant change in EV production was observed. Therefore, EVs could be a potential target to enhance the immune response to P. falciparum and prevent the spread of infection.